Aircraft are generally designed with gentle curves and smooth surfaces to enable streamlined airflows and decreased drag, thereby increasing overall fuel efficiency of the aircraft while in flight. On some aircraft that experience airflow disturbances or separation, vortex generators have been used to reduce aerodynamic instabilities and associated drag and noise.
Aircraft also contain internal heat generating components and systems, such as Fuel Cell Emergency Power Systems (“FCEPS”). Typically, aircraft dissipate this heat to the atmosphere through air heat exchangers. These heat exchangers tend to be heavy, which reduces available transport capacity of the aircraft. Also, the heat exchangers tend to have a large surface area to counter inhibited mixing and heat dissipation caused by heated airflow boundary layers.